JazzSinger
I open something I don't need at the moment, say the piano roll, and undock it using the double-window icon on the right of the multidock. The multidock now disappears...
It doesn't disappear completely but is removed from the main window. What you've actually done is given the Multidock it's own floating window containing any and all open views aside from the main view (Track View). This works great with multiple monitors but not so great with one.
JazzSinger
(Strangely, draggîng the tab off the multidock does not work).
Dragging one view from the Multidock only undocks that one view. If you close or drag away all the Multidock views, the empty Multidock bar will reappear in the main view.